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Hi, David,

Thanks for going private with your good advice, perhaps you didn't want to embarrass me. But as you will see, no problem, so I'll go public, imho it's too important a subject not to be aired.

I use Maxim DL to stack my images, normally using median combination. But with this particular image being taken in the short period of Astronomical Twilight, I didn't really have enough subs for that to do a complete job. Sigma clip was marginally better, but the brightest trails still left a faint remnant which I had to work on in Photoshop. I would have been better with twice as many 5 minute subs instead of the small number of 10 minute ones.

For example the attached image is a single calibrated green sub frame (reduced to 1/3 size). Just a couple of trails, but one of them exceedingly bright, so as there were only 4 green subs, the resultant RGB colour combine contained a faint green streak which had to be further worked on.

It would appear that those who are now using CMOS sensors generally have many more but shorter subs than we CCD dinosaurs are used to working with, so the rejection algorithms have a much better chance of doing a good job. But of course those large amounts of data need very powerful up to date computers with a lot of memory to process the data. My desktop is quite well specified, Windows 7 64 bit, i7 processor, but with 'only' 6 GB RAM not all that well equipped for handling massive amounts of data, although since I recently fitted an SSD has improved quite a bit, and it zips along with my relatively modest requirements. The maximum RAM the computer can take is 8 GB, so very little room for improvement there.

I have to say the general feeling I'm getting both from this forum and Stargazers Lounge is that 'we're all right Jack', we can beat the satellite trails with clever processing. But that's not really the point is it? As Olly Penrice states in my SGL thread 'The satellite situation is like the plastic situation. We are drowning in plastic, yet still we churn it out.' Here is the thread for those interested in having a look:



It's bad enough for us amateurs at home, and must be particularly annoying for those lucky enough to have their own remote observatories at dark sites, with the attendant costs and initial hard work setting it all up. How much worse must it be for the large professional observatories with their huge multimillion pound telescopes!

Cheers,

Peter


Approx. 55 deg N, 2 deg W (Northumberland, UK)